破片模拟弹侵彻钢板的有限元分析

根据破片模拟弹侵彻钢板的实验研究,采用MSC.Dytran对破片模拟弹侵彻钢板的侵彻过程、侵彻特性、钢板的破坏模式以及弹体的侵彻速度、靶板的侵彻阻力进行了有限元分析,并将分析结果与实验结果进行了比较.分析结果表明,破片模拟弹冲击钢装甲的侵彻过程可大致分为初始接触、弹体侵入、剪切冲塞和穿甲破坏4个阶段.有限元分析的破片模拟弹侵彻特性及靶板破坏模式与实验观测结果有较好的一致性,在靶板破口的正面,与弹体平面凸缘两端接触的部分,变形以剪切为主,而与切削面接触的部分,以挤压变形为主;靶板破口背面为剪切冲塞破坏;有限元模拟的弹体剩余速度与实验结果吻合较好,弹体侵彻过程中弹靶作用界面的速度和侵彻速度近似呈线性变化.有限元分析结果还表明,采用适当的模型,有限元法能较好地模拟破片模拟弹侵彻钢板的侵彻过程、侵彻特性以及钢板的破坏模式.     

HgCdTe探测器激光辐照响应机理研究进展

以光导型和光伏型HgCdTe光电探测器为研究对象,分别用连续波激光和脉冲激光开展了辐照效应实验研究。使用平衡能量流体动力学模型数值模拟了光电探测器对辐照激光的响应过程,数值模拟结果与实验结果符合较好。报道了连续波激光辐照下的热效应和脉冲激光引致的损伤效应等典型实验和数值模拟研究结果,总结了光电探测器对辐照激光的响应机理及其应用前景。     

连续激光辐照InSb的热损伤研究

在建立高斯型连续激光辐照半导体材料InSb物理模型的基础上,采用解析解的形式计算了圆柱形InSb靶板的三维温度场。通过数值分析得出了在连续激光辐照时,InSb发生的是熔融损伤的结果,并计算出相应的损伤阈值。对理论计算与实验结论进行了比较,验证了理论模型的合理性。     

连接方式对舰船舷侧复合装甲结构抗穿甲性能的影响

为探讨连接方式对舰船舷侧外设复合装甲结构抗穿甲性能的影响,采用均质钢板粘结或叠层接触前置复合材料板分别模拟舰船舷侧粘敷或铆接固定两种连接方式的外设舷侧复合装甲,并结合低速弹道实验,分析了两种连接方式下组合靶板的穿甲破坏模式和抗弹性能,得到了球头弹穿透叠层接触组合靶板的剩余速度理论预测公式。在此基础上,将该理论预测公式计算结果与实验结果进行了比较分析。结果表明:两种组合靶板中前置装甲板的穿甲破坏模式差异不大,但叠层接触组合靶板中钢质背板穿孔周围的蝶形变形范围及其变形程度均较粘结组合靶板中的钢质背板要大;叠层接触组合靶板的整体抗弹吸能要大于粘结组合靶板;弹丸穿透叠层接触组合靶板的剩余速度理论预测值与实验结果吻合较好。     

陶瓷破片侵彻钛合金薄靶实验及数值模拟研究

为了研究非金属陶瓷破片对钛合金薄靶的侵彻效能,采用弹道冲击实验与有限元数值模拟相结合的方法,开展了破片直径和着靶角度对靶板破坏形态及弹道极限的影响研究。结果表明：在弹道极限情况下,陶瓷破片对钛合金薄靶的侵彻形态主要分为瓣裂穿孔和冲塞穿孔。其中,钛合金靶厚度为0.5～0.8 mm时,靶板的破坏形式主要以瓣裂穿孔为主,靶板厚度为1.0～1.5 mm时,对靶板的破坏形式为瓣裂穿孔和冲塞穿孔2种方式的耦合状态,靶板厚度为2.0 mm时,靶板的破坏方式为冲塞穿孔。随着破片直径的增大,陶瓷破片对靶板的弹道极限(V₅₀)逐渐减小,靶板背面造成的盘式隆起越明显。同时,随着陶瓷破片着角的增加,侵彻靶板的V₅₀也随之增加,当着角大于75°时,破片发生跳飞现象。研究结论对于反卫星武器战斗部威力设计具有重要意义。     

1．06μm连续激光辐照GaAs探测器的理论研究

建立了高斯型连续激光辐照GaAs探测器物理模型,近似解析计算了圆柱形GaAs靶板的三维温度场.数值分析了激光辐照时GaAs探测器的信号异常及熔融损伤的情况,并计算了相应的损伤阈值.理论计算与实验结论能够精确的一致,理论模型为评论同类激光效应以及激光对抗的激光加固提供了参考.     

切向空气气流对激光辐照碳纤维复合材料的影响

实验研究了靶材表面存在和不存在切向空气气流时,975nm连续激光对碳纤维增强树脂基复合材料的辐照效应,发现切向气流的加载有利于激光对碳纤维复合材料的破坏.从理论上对激光辐照下碳纤维复合材料的破坏机理进行了初步分析,基于碳的氧化特性和氧化反应机理,推导了碳纤维的氧化速率方程.采用改进的光滑粒子方法,对激光辐照下复合材料树...     

强激光辐照下双层壳体温度场和应力场的数值模拟

强激光照射下结构的热力学响应是激光应用技术的重要问题.本文采用三维有限元分析模型,对双层圆柱壳在强激光辐照下的温度场、应力场和位移场进行了数值模拟与分析.分析时考虑了材料参数随温度的变化特性,主要探讨了不同光斑直径下双层壳温度场的变化趋势,研究了外层壳厚度、热膨胀系数、弹性模量和泊松比等参数对内层壳光斑中心处温升、应力...     

组合激光作用下CdS探测器破坏阈值实验研究

采用组合激光(即响应波段内532nm激光和响应波段外1319nm激光)对光导型CdS探测器进行辐照,测量了CdS探测器的破坏阈值。当1319nm激光辐照功率密度保持不变时,波段内激光的加入明显缩短了CdS探测器被破坏时激光所需的辐照时间,并且随着532nm激光功率密度的不断增大,辐照时间先减少后增加;当1319nm激光辐照时间保持不变时,随着532nm激光功率密度的增大,CdS探测器被破坏所需的1319nm激光功率密度先减小后增大,但恢复值仍比没有532nm激光加入时要小,说明了波段内激光的增强作用。上述两种变化趋势与相同条件下探测器的电压响应变化规律一致。     

强激光脉冲引起铝的弹塑性流动及层裂的计算

计算了强激光脉冲辐照铝靶时,引起铝靶的弹塑性流动及层裂。激光脉宽30毫微秒,靶厚0.5厘米,对四种功率密度的激光进行了计算。计算中利用了 von Mises 屈服条件和损伤积累断裂准则。得出了激光功率密度与第一痴片厚度、靶板破坏区宽度、损伤区宽度间的定性关系,并与我们过去的结果做了比较。     

Statistical variability and fragility assessment of ballistic perforation of steel plates for 7.62 mm AP ammunition

The paper describes field test results of 7.62 × 51 mm M61 AP (armour piercing) ammunition fired into mild steel targets at an outdoor range. The targets varied from 10 mm to 32 mm in thickness. The tests recorded penetration depth, probability of perforation (i.e., complete penetration), muzzle and impact velocities, bullet mass, and plate yield strength and hardness. The measured penetration depth exhibited a variability of approximately ±12%. The paper then compared ballistic test results with predictive models of steel penetration depth and thickness to prevent perforation. Statistical parameters were derived for muzzle and impact velocity, bullet mass, plate thickness, plate hardness, and model error. A Monte-Carlo probabilistic analysis was then developed to estimate the probability of plate perforation of 7.62 mm M61 AP ammunition for a range of impact velocities, and for mild steels, and High Hardness Armour (HHA) plates. This perforation fragility analysis considered the random variability of impact velocity, bullet mass, plate thickness, plate hardness, and model error. Such a probabilistic analysis allows for reliability-based design, where, for example, the plate thickness with 95% reliability (i.e. only 1 in 20 shots will penetrate the wall) can be estimated knowing the probabilistic distribution of perforation. Hence, it was found that the plate thickness to ensure a low 5% probability of perforation needs to be 11–15% thicker than required to have a 50/50 chance of perforation for mild steel plates. Plates would need to be 20–30% thicker if probability of perforation is reduced to zero.     

冲击波和高速破片联合作用下固支方板毁伤效应数值模拟

为探讨固支方形钢板结构在空爆冲击波和高速破片联合作用下的动态响应过程及变形破坏模式,利用有限元分析软件ANSYS/LS-DYNA,开展了空爆冲击波和高速破片对固支方板的联合作用数值模拟计算,阐述了固支方板在联合载荷作用下动态响应过程的2个阶段,以及在不同爆距下的变形破坏模式和特点。结果表明,随着爆距增加,在破片密集作用区内,钢板的破坏模式存在从集团冲塞破口到部分穿孔边界撕裂联通,再到无穿孔边界撕裂现象的转换。     

运动激光辐照圆柱薄壳温度场的数值模拟

对圆柱薄壳在四种不同运动模式激光源辐照下的温度场分布进行了分析研究。运用傅立叶级数展开法推导了在不同运动模式激光源作用下圆柱薄壳温度场的解析表达式,并对该解析表达式进行了编程计算,其计算结果与有限元解吻合良好。详细分析了旋转角速度与平动速度对圆柱壳温升分布的影响,发现在往复运动加热模式下光斑区域的温升变化最为剧烈。计算结果为导弹的抗激光辐射提供了理论依据。     

温度对半导体激光器退化的影响

采取等效电路模型仿真和加速退化试验相结合的方法研究温度对半导体激光器不同退化模式的影响规律。针对半导体激光器有源区退化和腔面退化进行分析,发现有源区退化会使半导体激光器阈值电流增大,而腔面退化会使半导体激光器斜率效率减小;进行了半导体激光器热特性建模与仿真,发现温度升高会使半导体激光器阈值电流增大;利用半导体激光器加速退化试验平台进行了半导体激光器加速退化试验。仿真与试验结果证明:温度升高会加剧半导体激光器腔面退化,而对有源区退化无显著影响。上述结论对进一步完善半导体激光器温度-退化仿真模型,研究温度对半导体激光器退化的作用机理和防护措施有积极作用。     

基于逆合成孔径成像激光雷达的自旋小目标成像系统

为了获得毫米级自旋小目标的清晰成像,采用逆合成孔径成像激光雷达技术设计了基于距离向数据与方位向数据相融合的图像重建系统。系统采用大带宽、窄线宽光纤激光器配合调制器实现激光脉冲的线性调频,利用光外差原理对回波信号进行采集处理。结合自旋目标的运动特性,给出了含有自旋分量的回波信号函数方程,并将该分量引入传统的R-D算法中实现了对自旋目标的ISAIL二维图像的重建。实验采用毫米级铝条构成被测小目标,通过步进电机及带倾角的转台完成运动及自旋模拟。实验结果显示,当目标固定时,可通过回波能量数据获得一维距离向图像,与被测目标的4个特征点位置一致。当目标运动时,通过数据压缩并代入自旋参量,最后通过R-D算法可以获得可识别的ISAIL二维图像,验证了系统符合自旋小目标成像的设计要求。     

A three-stage model for the perforation of finite metallic plates by long rods at high velocities

A three-stage theoretical model is presented herein to predict the perforation of a thick metallic plate struck normally by a long rod at high velocities. The model is suggested on the basis of the assumption that the perforation of a thick metallic plate by a long rod can be divided into three stages: (1) initial penetration; (2) plug formation and (3) plug slipping and separation. Various analytical equations are derived which can be employed to predict the ballistic limit, residual velocity and residual length of the long rod. It is demonstrated that the present model predictions are in good agreement with available experimental results for the perforation of finite steel targets struck normally by steel as well as tungsten alloy long rods at high velocities. It is also demonstrated that the dynamic maximum shear stress of a plate material has strong effect on plug formation and plug thickness which, in turn, exerts considerable influence on the residual velocities and lengths of a long rod at impact velocities just above the ballistic limit.     

Investigation on the spatial distribution characteristics of behind-armor debris formed by the perforation of EFP through steel target

The behind-armor debris (BAD) formed by the perforation of an EFP is the main damage factor for the secondary destruction to the behind-armor components. Aiming at investigating the BAD caused by EFP, flash X-ray radiography combined with an experimental witness plate test method was used, and the FEM-SPH adaptive conversion algorithm in LS-DYNA software was employed to model the perforation process. The simulation results of the debris cloud shape and number of debris were in good agreement with the flash X-ray radiographs and perforated holes on the witness plate, respectively. Three-dimensional numerical simulations of EFP's penetration under various impact conditions were conducted. The results show that, an ellipsoidal debris cloud, with the major-to-minor axis radio (a/b) smaller than that caused by shaped charge jets, was formed behind the target. With the increase of target thickness (h) and decrease of impact velocity (v₀) and obliquity (θ), the value of a/b decreases. The number of debris ejected from target is significantly higher than that from EFP. Based on the statistical analysis of the spatial distribution of the BAD, An engineering calculation model was established considering the influence of h, v₀ and θ. The model can with reasonable accuracy predict the quantity and velocity distribution characteristics of BAD formed by EFP.     

重复脉冲激光辐照InSb(PV)型探测器的热损伤

在建立高斯型重复脉冲激光辐照InSb(PV)型探测器物理模型的基础上,采用近似解析解的形式计算了圆柱形InSb靶板的二维温度场。通过数值分析得出了在激光辐照时,InSb(PV)型探测器的温升与时间的关系,并计算出相应的损伤阈值。研究表明:在高斯型重复脉冲激光辐照下,损伤阈值受到脉冲数目、宽度、重复频率以及脉冲激光光斑半径的影响,InSb(PV)型探测器会发生熔融损伤,发生于迎光面的光斑中心。对于一定厚度胶层的InSb(PV)型探测器,只有强度大于一定阈值时重复脉冲激光的辐照才可能发生熔融损伤,越薄的胶层对应的损伤阈值越大。为了增加InSb(PV)型探测器的激光对抗能力,应该减小胶层厚度。